Silent ischemia as a marker for early unfavorable outcomes in patients with unstable angina.

We examined the prevalence and prognostic importance of silent myocardial ischemia detected by continuous electrocardiographic monitoring in 70 patients with unstable angina. All the patients received intensive medical treatment with nitrates, beta-blockers, and calcium-channel blockers. Continuous electrocardiographic recordings were made during the first two days in the coronary care unit to quantify the frequency and duration of asymptomatic ischemic episodes, defined as a transient ST-segment shift of 1 mm or more. Thirty-seven patients (Group 1) had at least one episode of silent ischemia, and the other 33 patients had no silent ischemia (Group 2). Over the subsequent month, myocardial infarction occurred in 6 patients in Group 1 and in only 1 in Group 2 (P less than 0.01); bypass surgery or angioplasty was required for recurrent symptomatic angina in 10 patients in Group 1 and only 3 in Group 2 (P = 0.02). Survival-curve analysis demonstrated that silent ischemia was associated with these outcomes (P less than 0.002), and multivariate analysis showed that silent ischemia was the best predictor of these outcomes among the 15 variables tested (P less than 0.002). Patients in Group 1 with 60 minutes or more of silent ischemia per 24 hours had a worse prognosis than those with under 60 minutes per 24 hours (P = 0.04). Silent ischemia occurred in more than 50 percent of our patients with unstable angina, despite intensive medical therapy, and it identified a subset who were at high risk for early unfavorable outcomes.

[1]  J. Kalbfleisch,et al.  The Statistical Analysis of Failure Time Data , 1980 .

[2]  M. Winniford,et al.  Continuous electrocardiographic monitoring in patients with unstable angina pectoris: Identification of high-risk subgroup with severe coronary disease, variant angina, and/or impaired early prognosis. , 1982, American heart journal.

[3]  R. Testa,et al.  Vasospastic ischemic mechanism of frequent asymptomatic transient ST-T changes during continuous electrocardiographic monitoring in selected unstable angina patients. , 1982, American heart journal.

[4]  S. Chierchia,et al.  Sequence of Events in Angina at Rest: Primary Reduction in Coronary Flow , 1980, Circulation.

[5]  R. Russell,et al.  Coronary anatomy and arteriography in patients with unstable angina pectoris. , 1978, American Journal of Cardiology.

[6]  M. Lesch,et al.  Intravenous nitroglycerin for the treatment of angina at rest unresponsive to standard nitrate therapy. , 1983, The American journal of cardiology.

[7]  E. Shapiro,et al.  Intracoronary thrombolysis 3 to 13 days after acute myocardial infarction for postinfarction angina pectoris. , 1985, The American journal of cardiology.

[8]  W. Neill,et al.  Medical versus surgical therapy for acute coronary insufficiency. A randomized study. , 1975, The New England journal of medicine.

[9]  R. Gorlin,et al.  The intermediate coronary syndrome: clinical, angiographic and therapeutic aspects. , 1973, The New England journal of medicine.

[10]  J. Heinsimer,et al.  Intravenous Nitroglycerin in the Treatment of Spontaneous Angina Pectoris: A Prospective, Randomized Trial , 1983, Circulation.

[11]  J. Deanfield,et al.  Analysis of ST-segment changes in normal subjects: implications for ambulatory monitoring in angina pectoris. , 1984, The American journal of cardiology.

[12]  R. Rosati,et al.  Unstable angina pectoris: National cooperative study group to compare surgical and medical therapy: II. In-Hospital experience and initial follow-up results in patients with one, two and three vessel disease , 1978 .

[13]  S. Chierchia,et al.  MYOCARDIAL ISCHAEMIA DURING DAILY LIFE IN PATIENTS WITH STABLE ANGINA: ITS RELATION TO SYMPTOMS AND HEART RATE CHANGES , 1983, The Lancet.

[14]  P. Serruys,et al.  Emergency coronary angioplasty in refractory unstable angina. , 1985, The New England journal of medicine.

[15]  S Chierchia,et al.  Impairment of myocardial perfusion and function during painless myocardial ischemia. , 1983, Journal of the American College of Cardiology.

[16]  E. Braunwald,et al.  The Stunned Myocardium: Prolonged, Postischemic Ventricular Dysfunction , 1982, Circulation.

[17]  B. Rosner,et al.  Nifedipine and conventional therapy for unstable angina pectoris: a randomized, double-blind comparison. , 1984, Circulation.

[18]  G. Santoro,et al.  Silent myocardial ischemia during ambulatory electrocardiographic monitoring in patients with effort angina. , 1983, Journal of the American College of Cardiology.

[19]  C. Marchesi,et al.  Coronary Artery Spasm as a Cause of Acute Myocardial Ischemia in Man , 1975 .

[20]  A. Maseri,et al.  Transient Transmural Reduction of Myocardial Blood Flow, Demonstrated by Thallium‐201 Scintigraphy, as a Cause of Variant Angina , 1976, Circulation.

[21]  R. W. Brower,et al.  Nifedipine in the treatment of unstable angina, coronary spasm and myocardial ischemia. , 1981, The American journal of cardiology.

[22]  D. Waters,et al.  A randomized study comparing propranolol and diltiazem in the treatment of unstable angina. , 1985, Journal of the American College of Cardiology.

[23]  D. Tzivoni,et al.  Early detection of silent ischaemic heart disease by 24-hour electrocardiographic monitoring of active subjects. , 1974, British heart journal.

[24]  N. Breslow.  A generalized Kruskal-Wallis test for comparing K samples subject to unequal patterns of censorship , 1970 .

[25]  E. Antman,et al.  Nifedipine therapy for coronary-artery spasm. Experience in 127 patients. , 1980, The New England journal of medicine.

[26]  J. Flaherty,et al.  Crossover from intravenous to transdermal nitroglycerin therapy in unstable angina pectoris. , 1985, The American journal of cardiology.

[27]  P. Gazes,et al.  Preinfarctional (Unstable) Angina—A Prospective Study— Ten Year Follow‐Up: Prognostic Significance of Electrocardiographic Changes , 1973, Circulation.

[28]  J. Weiss,et al.  Nifedipine in unstable angina: a double-blind, randomized trial. , 1982, The New England journal of medicine.

[29]  E. J. Brown,et al.  Global and regional left ventricular ejection fraction abnormalities during exercise in patients with silent myocardial ischemia. , 1983, Journal of the American College of Cardiology.

[30]  S. Chierchia,et al.  Coronary vasospasm as a possible cause of myocardial infarction. A conclusion derived from the study of "preinfarction" angina. , 1978, The New England journal of medicine.

[31]  E. Shapiro,et al.  Effect of the addition of propranolol to therapy with nifedipine for unstable angina pectoris: a randomized, double-blind, placebo-controlled trial. , 1986, Circulation.

[32]  M. Weisfeldt,et al.  Variables predictive of successful medical therapy in patients with unstable angina: selection by multivariate analysis from clinical, electrocardiographic, and angiographic evaluations. , 1984, Circulation.

[33]  C. Pepine,et al.  Transient asymptomatic S-T segment depression during daily activity. , 1977, The American journal of cardiology.

[34]  R A Wilson,et al.  Transient ST-segment depression as a marker of myocardial ischemia during daily life. , 1984, The American journal of cardiology.